1. Field of the Invention
The present invention refers to a method for depositing of barrier layers on a plastic substrate comprising a first coating step for depositing a first barrier layer comprising a metal and a second coating step for depositing a second barrier layer comprising a resin and relates to a coating device for carrying out such a method as well as to a layer system produced by this method.
2. Prior Art
Composite foils made from plastic substrates and barrier layers deposited thereon for preventing moisture and oxygen passing the composite foil are known in packaging industries for packing food, chemical goods, and pharmaceuticals as well as technical or other agricultural products. In order to protect the packed goods from moisture and oxygen which might cause environmental degradation of the products, different layer systems forming the composite foil are used. Examples are given in WO 02/02315 A1, DE 43 28 767 A1, DE 199 351 81 A1, DE 199 170 76 A1 or JP 2006044130 A. One commonly used layer system comprises a plastic foil as a substrate onto which a first barrier layer made of aluminium or aluminium oxide is deposited. On the first barrier layer a second barrier layer is provided for. The second barrier layer is made of a melamine resin. Both barrier layers may be deposited at the surface of the plastic foil by evaporation processes. However, although such a layer system comprises good protection for the goods packed by such a foil with respect to moisture and oxygen, pure adhesion of the melamine resin on the aluminium or alumina layer is a serious drawback.